A chemical amplification photosensitive composition is a pattern forming material capable of forming a pattern on a substrate by producing an acid in the exposed area upon irradiation with radiation such as far ultraviolet light and through a reaction using this acid as the catalyst, changing the solubility in a developer to differ between the active radiation-irradiated part and the non-irradiated part.
In the case of using a KrF excimer laser as the exposure light source, a resin having small absorption in the region of 248 nm and having a basic skeleton of poly(hydroxystyrene) is primarily used as the main component and therefore, this is an excellent system capable of forming a good pattern with high sensitivity and high resolution compared with conventional naphthoquinonediazide/novolak resin systems.
In the case of using a light source of emitting light at shorter wavelengths, for example, in using an ArF excimer laser (193 nm) as the light source, a satisfactory pattern cannot be formed even by the above-described chemical amplification system because the compound having an aromatic group substantially has large absorption in the region of 193 nm.
In order to solve this problem, a resist containing an alicyclic hydrocarbon structure has been developed for use with an ArF excimer laser. For example, JP-A-2003-167347 and JP-A-2003-223001 describe a composition comprising a repeating unit containing an acid-decomposable group having a polycyclic structure and a non-acid-decomposable repeating unit. In JP-A-2001-56556, a combination of a specific resin and a solvent is studied with an attempt to reduce development defects, edge roughness and iso/dense bias.
Furthermore, the recent demand for a resist pattern with high resolution of 0.11 microns or less requires the development defect of the resist pattern after development to be more reduced than ever before, in addition to the above-described properties.
Development defects are troubles in general detected when the resist pattern after development is observed from directly above, for example, by a surface defect inspection apparatus (“KLA”, trade name) manufactured by KLA-Tencor Ltd. This trouble includes, for example, bubble or dust after development and bridges between gaps in resist patterns.
Also, the ArF resist in recent years has a problem that a residue (hereinafter, sometimes referred to as a “scum”) is found in the removed portion (space portion). If this scum is present, the pattern is not correctly transferred after etching, which hinders the production of a device.
In order to reduce these development defects and scum, studies and improvements have been heretofore made, mainly focusing on the resist composition such as resin component, acid generator component and solvent component of the resist composition (see, JP-A-2001-56556), but more improvements are being demanded.